Manufacture of soap powder



May 12, 1931.

R. L. HOLLIDAY MANUFACTURE OF SOAP. POWDER Filed April 19, 1926 ENTOB MUM M4M ATTORNEY Patented May-12.1931 I 1,804,932

UNITED STATES PATENT OFFICE ROBERT L. HOLLIDAY, or NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, T COLGATE-PALMOLIVE-PEET COMPANY, or cmcaco, ILLINOIS, A CORPORATION 01 DELAWARE, AND THE raoc'rra & GAMBLE COMPANY. or CINCINNATI, 01110, A coa- PORATION or 01110 MANUFACTURE 0s soar rownnn Application filed April 19, '1926. Serial No. 102,861.

The present invention relates to the manuare cooled below the temperature of crystal factnre of a soap powder product contain- 'lization of the sodium carbonate ingredient ing soda ash, or the like, and has to do parand are thus reduced to the form ofsolidified ticularly with themanufacture of the dry particles or fragments. The action which product by a method radicallyditlerent from takes place is a crystallizing and hydrating a) the common methods heretofore'employed in action in all respects similar to that which octhe commercial production of this type of curs in the usual operation of reducing the product, and by a method which permits of mixture to solid form by the cold roll process. systematic and accurate control of the con- The cooling or chilling agent which is emditions of the process atall times. ployed is refrigerated air or, in certain inon Soap powders or washing powders, as disstances, untreated atmospheric air if atmostinguished from ordinary soap produced 111 pheric conditions of temperature and hupowdered form, contain a certain quantity midity happen to be favorable. In these of soda ash (sodium carbonate). Such soap processes of reducing the soap and soda powders are mixtures of soda ash, soap and ash mixture to solid form by cooling to effect 5 Water. The type of soap powder in general crystallization, a slight amount of evaporause at the present time contains usually from tion occurs incidentally by reason of the con- 30% to 40% of water. In the ordinary proctained heat in the soap mixture and by reason ess of manufacture the soda ash is added of the fact that the chilling air or the at- 'to the hot soap stock and the water content mosphorc surrounding the chilling rolls takes 70 of the mixture is controlled until the desired up a small amount of the Water present in proportion of ingredients is attained. The the material. The amount of evaporation hot mixture is then chilled by spreading it which takes place is small and is largely deupon refrigerating cylinders or rolls through pendent upon the particular atmospheric conwhich a cold liquid such as brine is circuditions which prevail at the time the process 75 lating. The chilling action of the cold rolls is being carried out. An evaporation of from effects a certain crystallization of the sodium about 2% to 5% or less calculated on the carbonate with an amount of the water in- Weight of the mixture about represents the corporated into the crystals as Water of range of conditions usually encountered in crystallization. The resulting product as commercial operation. The old style soap 80 scraped from the rolls is intended to be powders were sometimes made by a process solidified and friable and is subjected to a which involved a certain drying of the prodbreaking up and aerating operation, as by not to produce it with a low Water content. shoveliing over manually, to reduce it to a It has also been proposed as a matter of reasonably finely divided form for markettheory to produce soap powder by spraying a ing as a soap powder. The reduction of the ,hot liquid soap and soda ashmixture into athot liquid mixtureto solidified form upon mosphere or into a heated chamber in the the chilling rolls is essentially a crystallizamanner previously proposed for producing tion and hydration operation as distinguished powdered soap, but such a process cannot be 40 from drying by evaporation. The cooling of successfully conducted due to impossibility of the mixture creates a condition favorable to solidifying the product With a proper water the crystallization of the sodium carbonate content, absence of control of humidity conand, as the sodium carbonate crystallizes, it ditions, efi'ect of atmospheric conditions, and

incorporates as water of crystallizationthe the like, and, asfar as I am' aware, such a major portion of Water in the batch. process has never been employed in the pro- It has also been proposed to produce soap duction of the commercial product.

powder of this typeby disintegrating the usual The present invention is in part based upon hot soap and soda 'ash mixture and subjecting the discovery that soap powder, that is, a powit while in such disintegrated condition to the dered soap .product consisting of a mixture 5 action of a cooling gas wherein the particles of soap, soda ash and Water can, in fact, be

produced by preparing a fluid mixture of the.

by products of this class and having certain additional desirable properties, such as greater ease of solubility, and the like, may be easily and conveniently produced throughout the entire range of moisture content required in the commercial powder product.

The soap and soda ash mixture is preferably prepared with an excess of water. It is prepared in such condition that it is free flowing and is capable of being broken up into small uniform liquid drops by spraying in the manner above described. In the ordinary process of manufacture the soda ash and soapmixture before chilling is a paste which may contain say 43% by weight of water. A small amount of this water is evaporated incidentally during the manufacturlng operations so that the ultimate product may contain say of water. A very important practical difliculty is presented by the fact that, in order to obtain the ultimate product in a solidified condition which will retain its powder form at all satisfactorily, the mixture before, chilling must be so restricted in water content as to bevery difiicult of handling in pipe lines and the like. Much trouble is experienced through solidification of the original mixture in the pipe lines and tanks. When the initial mixture is of a consistency which'permits handling of it at all, much difficulty is encountered in getting the material to assume solid form as it comes out of the chilling process.

- In warm weather when the humidity is high it is often extremely difficult to accomplish the solidification of the product to such extent that it may be used commercially. The

process of the present invention, however,

provides for the compounding of the initial mixture in such proportions as to' render it perfectly fluent and easy of handling, evaporating out of it by means of applied heat any desired amount of water to thereby directly produce an apparently dry soap powder of any desired water content which will permit the product to be in solid form, the water content of the material being to a considerable extent absorbed intolthe product as water of crystallization in the sodium carbonate constituent. The essential features of the process are the proper breaking up of the -initial mixture into liquid drops of appropriate size and form the evaporation of theseidrops of material to the desired extent by a heatedinitial mixture in condition sufficiently fluid to avoid all troubles of piping and handling, accurate control of the amount of moisture in the ultimateproduct independently of atmospheric conditions, and the like. The requisite control in the drying of the product is accomplished by drying'the mixture in a gaseous drying medium.

It is important that the particles of soap powder stock be treated'in a current of circulating gas which carries away the moisture evaporated from the particles and flows in such fashion that, when continued operation of the apparatus has been established, the conditions of the process such as humidity, temperature, state of dryness of the soap powder particles, etc., at any given place in the drying tower are, for all practical purposes, substantially constant. It is also important that the current of gas in which the soap powder particles are treated be passed through the drying tower in a common direction of flow with the particles so that the particles are carried in and by the gas current and are ,thus positively propelled through and out of the apparatus in a. definite and regular manner. With this arrangement the gas first contacts with the particles at substantially its highest temperature and last contacts with the solidi ficd soap powder particles at substantially its lowest temperature. The particles under treatment are carried through the tower in a positive flow, and thus all of the particles remain-in the drying tower for substantially the same length oftime and are subjected to substantially identical treatment. With this condition existing the air current may be controlled and conditioned asto rate of flow, volume, temperature, moisture content, and the like, so that any desired variations in' the ultimate product may be obtained by variation of one or all of these variables. The process also provides for re oving the treated soap powder particles together with the gas which carries them, as well as the moisture contained in it, from the drying tower in intermixed condition so that collection of the dried particles may proceed as desired at a point-removed from the hot drying tower. The collection problem is simplified by reason of the fact that all of the solids may pass out of the drying tower at one point. In the matter of conditioning the air current in -which the soap powder particles are carried in suspension cooling gas may be admitted as desired along the length of the tower so that after the particles have been reduced to a desired moisture content they may also be suitably reduced in temperature to assure their production in non-sticking form whereby the soap powder product will be a finely divided regular apparently dry free flowing powder. The present process therefore pro vides for a uniform treatment of the particles of soap powder stock to produce a uniform product which may be controlled to possess within reasonable limits any desired moisture content and which may be successfully and easily produced commercially at all times and in all weather conditions in the form of an apparently dry solid easily handled powder product. 7

The accompanying drawing illustrates more or less diagrammatically an apparatus in which the present process may be carried out as a continuous operation requiring but a very small proportion of the labor required in the present commercial process-es of man-- ufacturing soap powder. The powder stock,

' after having been produced in the usual course of the manufacture of the product and having been prepared with a sufficient amount of water to adapt it for treatment by the present process, is delivered to a tank 1 provided with an agitator 2 driven continuously by motor 3 for the purpose of main taining the entire body of stock in a thoroughly mixed homogeneous condition. The tank 1 is steam jacketed as indicated at 4 for the purpose of maintaining the stock at a.

suitable temperature. The liquid stock from the tank 1 is passed through line 5 into the drying tower 6. The breaking up or spraying of the liquid stock into the form of small uniformly,constituted particles is effected by means of spray nozzles 7 located in the upper part of the drying tower 6 and arranged about the tower in such fashion as to uniformly distribute the spray throughout the entire upper portion of the tower. In the apparatus here shown the flow of soap "(0 the nozzles 7 occurs due to gravity, and the breaking up of the material into the form of a spray is eifected bymeans of atomizing air or steam supplied to the nozzles 7 as indicated at 8. The drying gas consists of at-- mospheric air which is heated in the furnace 9 and is then passed into the upper portion of the drying tower 6 through a passage or duct 10. The furnace 9 may, for instance, be oil fired and the air passing through it may be heated by causing it to pass along one side of heat transferring surfaces which i on the other side are heated by direct contact with the products of combustion. The heated air entering the upper portion of the tower contacts with the atomized soap liquid is- Y suing from the spray nozzles 7, at substantially its hottest temperature and, while drying of the soap powder particles is taking place,

the drying air, the particles entrained there in and the moisture absorbed in the air pass downwardly through the drying tower in a common direction of flow and pass out of the tower at the discharge opening 11 in intermixed condition. This discharge stream of material passes through duct 12 into collector 13, here shown as an ordinary cyclone into the barrel or other package or storage reservoir 19. The .flow through the entire apparatus is established by means of a motor operated fan 20 positioned at the discharge side of the bag collector 16 and passing the gas drawn from the collectors to atmosphere through stack 21.

The particles of the sprayed liquid are carried-in positive flow through the tower 6 by the drying gas, and thus every particle is subjected to the drying treatment for sub-'1:

stant-ially the same length of time. Condi tions in the tower are'controlled by regulat ing the temperature and amount of the soap and soda ash material passed into the tower and the temperature and amount of drying air supplied to the tower. This, together with the concurrent flow of materials through the tower, effects a positive control of temperature and humldity conditions in the tower and permits the production of a uni- 3;

form product of anydesired moisture content. To further control the temperature conditions in the tower and particularly to restrict the evaporating action at the point where the moisture content of the soap particles has been reduced to a desired amount and for the purpose of cooling the dried particles to such extent as to render their collection in-dry powder form feasible, a supply of cooling air may be'admitted tothe tower .1.

as indicated at 22. The tower may be designed for the admission of this cooling air at. any one or more points along'the length of the tower and, by way of example in the apparatus here shown, the cooling air-is admitted near the bottom of the tower and consists of atmospheric air introduced by means of the power driven blower 23. In. some instances it may be "feasible to condition this air as, for instance, by heating to a certain degree before admitting it to the tower. At the bottom of the tower 6 below the discharge opening 11 is a motor driven disintegrator 24 designed to receive anyagglomerates or heavy particles which may possibly be to t e spra formed in commercial operation. Suchheavy particles will not be. drawn into the duct 11 but will. drop into the disintegrator 24 where they will be immediately broken up and caught in the air current which is drawn into the disintegrator through the opening 25. This apparatus furnishes a means for carrying out the present process as a continu- The product-is very uniform in appearance ous operation which requires no manual handling of the material from the initial raw stock to the finished powder product and, for that matter, to package form ready for shipping.

As an instance of a specific embodiment of the present process which has been successfully employed in the production on a commercial scale of a soap powder containing soda ash, the following conditions are given: The soap, soda ash, and water mixture was made up in such condition that it was sufiiciently liquid to flow readily and to be properly disintegrated by spraying. The mixture. contained about 13% of soap solids, 61% of water and 26% of dry sodium carbonate.

This gave a mixture having a total solid content of about 89% or 40%, and a corresponding water content of about Operation with. as low as say 50% of water is possible. In preparing the mixture the sodium carbonate was reduced to solu'tion in hot water,

and the hot soap stock in liquid or paste condition was mixed with it. This procedure has a distinct advantage over the rocedure now. used 1n the commerclal manu acture of soap powders wherein the soda ash is to a large extent added to the liquid soap stock in powder form for the reason that if added in the form of a solution the resulting mixture would contain a prohibitively high water content. This procedure avoids many important practical difficulties such as necessity of. grinding the soda ash, handlingand transportation of the bags of dry soda ash, and the like. With the present process the soda ash as received in the plant may immediately be thrown into a dissolving vat and the resulting soda ash solution piped and pumped to any part of the plant where it is needed. The soap stock used in the prepare tionof the soap about33% water so that the soap powder mixture as sprayed contained about 20% of soap stock, 26% of soda. ash, and 54% of addi-' tional water. This stock was preheated to a tem rature of about 180 F., and supplied nozzles from a tank in which the materia was iinderconstant agitation to maintain a homogeneous and uniform mixture. Spraying was accomplished by an atomizen The initial temperature. of the dry air was 150 F.., and the temperature after the drying treatment had been complete].

was about 100 or.110 F. '1 that is, almost atmospheric temperature. nitial temperatures of as high as 300 F. have been-success powder mixture containedand in texture. This uniformity and fineness of particle size is particularly evident upon comparing the product with soap powders of this type now available on the market. The

product is soft to the feel, goes into solution in water with a very small amountof stirring or agitation and floats on the surface when a mass of the powder is dropped into a receptacle containing water. When some of the powder product is compacted as by squeezing in the hand and is then introduced into water it quickly disintegrates or spreads out upon the water and dissolves. This is in contrast to ordinary commercial soap powders which when compacted in this way and placed in water retain their lump form and in the washing process act substantially like solid lumps of soap. The product obtained under the conditions just noted contained about 30% of moisture. The moisture content may be easily varied by varying the conditions of the process. For instance, aproduct ranging 1n moisture content from 4% to 40% may he produced by simple variations in the amounts of liquid and air and the temperature of the air. content depends not only upon the tempera ture differential along the length of the tower but upon the relative amounts of drying air and liquid which are supplied to the tower, the temperature to which the liquid-is pre- It will be understood that the moisture heated, and the like. Starting with a stock generally spherical shape. vThey are sufliciently stable to retain their shape during handling, and the spherical shape renders the product free flowing.v In contrast to the continuous amorphous structure of the powdered soap particles the particles of the soap powder are distinctly granular in nature.

This granular structure is apparent from the vexternal appearance of the magnified product. When the product is disintegrated under the microscope it breaks up into its component. grains and this granular .structure is evident down to the smallest particles of the material which can distinguished under ticle contacts with water it dissolves rapidly,

retaining its spherical form until it is completely dissolved. This action explains the ability of the product to go rapidly and easily into solution in water. The granular nature of the particles is probably due to the tendency of the soda ash ingredient of the powder to crystallize. The major part of the moisture content in the product probablyoccurs in the nature of water of crystallization in the soda ash ingredient. and it is therefore desirable to encourage the granular or crystalline structure in the particle for the purpose of facilitating incorporation into the product of a large percentage of water. This composite granular structure of the soap 5 powder particles is in marked contrast to the continuous amorphous structure of the particles of the powdered soap product. wherein no soda ash is present. v The present invention makes possible the reduction of the initial. soa'p and soda ash mixture to the form of a free flowing liquid which may readily be pumped and conveyed through pipe lines without danger of solidificatiou. In the ordinary commercial processes of soap powder manufacture the initial stock is very heavy and much difliculty is encountered due to its solidification. The present invention involves the provision of heated drying air. When atmospheric conditions are favorable soap powder stock may be solidified by passing it through atmospheric air but with the range of atmospheric conditions encountered in most localities the air is often too humid to permit successful possible the use of high temperature dryingair which is the economicalway of removing production of the soap powder in this man.

ner. The present invention makes possible the use of a free flowing liquid stock, makes moisture and also makes possible thecreation of conditions in the drying tower which are favorable for solidification of the soap powder with a high water content. This is done by spraying into the'high temperature, air a large quantity of the free flowing liquid stock so that the initial evaporation which occurs upon contact of the liquid spray with the heated air rapidly reduces the temperature of the air and increases its humidity so that favorable conditions are established. With this type of operation a large output ofsoap powder is obtained by the use of a relatively small quantity of air so that the amount of air which must-be handled by the fan and the collecting system is minimized.- This'procprocess for producing -merc1al basis 1n contmuous operation and from vantages of economy in evaporating costs, a

h free flowing initial liquid stock and a relatively small quantity of air through the fan and collectors per unit output of product.

The present'invcntion provides a practical soap powder on a comwith a total cost of operation and labor which is but a fraction of that involved in the ordinary commercial methods. The process makes possible the control of the conditions to which the material is subjected so that a uniform product of desired character may be obtained. The process is flexible in the sense that different sets of conditions can be estab lished in continuous operation to thereby produce products of different character as, for instance, of different water contents. The treatment of the product involves the evaporation of a substantial amount of water the initial stock, and the water thus evaporated is carried away so that substantially constant conditions of humidity and partial vapor pressures in the treating gas are maintained at any part of the apparatus.

' The product produced by the present process exhibits certain well-defined advantages over the ordinary soap powders, such as easier and more rapidly solubility, freedom from lumping or caking in water, uniformity in texture and particle form, and the like. tion contemplates product.

The expression in each claim, calling for the effecting removal of a portion of the moisture content of the sprayed powder mixture down to substantially 40% by bringing a current. of heated moisture absorbing treating gas into contact with the sprayed particles of the said 'mixture, is employed to define the removal of a portion of the moisture content from a degree above 40% to substantially 40% or lower, but is intended to be limited to a percentage as high as that required in the production of a relatively high moisture containing soap powder as distinguished from the --moisture content of spray dried soap such as that disclosed in applicants Reissue Patent 16,7 49, which usually contains from 3% to about 10% in the final product.

and soda ash with the soda ash in a predomi-' nating amount, which comprises preparing a soap and soda ash mixture with an amount of water sufficient to dissolve substantially all of the soda ash ingredient, the proportion of water being substantially in excess of the amount desired in the finished product so as to render the mixture free flowing to permit its being broken u into liquid drops by spraying and permitting itsbeing handled The invenboth the process and the through pumps and pipe lines with ordinary care without danger of solidification therein, sprayin said soap powder mixture to thus subdivi o it into drops, effecting removal of a portion of the moisture content of the sprayed soap powder'mixture down to sub stantially 40% b bringing a current of heated moisture a sorbing treating gas into contact with the sprayed particles of the said mixture, regulatin the total moisture absorbing capacity oi the treating gas relative to the total amount of water desired to be removed from the product being treated to thereby inhibit the removal of moisture from said particles of sprayed soap powder mix ture while the said mixture still has a relatively high water content, effecting incorporation of a major portion of said. relatively high Water content with the other constitucuts of the said soap powder mixture as water of crystallization to produce an ultimate product in apparently dry powder form by continuing the treatment of the sprayed soap powder mixture having said relatively high water content in a treating gas of controlled low moisture absorbing capacity until the said sprayed material under treat- 'ment has assumed an apparently dry condition, and then separating the apparently dry powder product from the treating gas to constitute the finished product.

2. The process of producing a dry appearing relativel high water containing soap powder pro uct consisting mainly of soap and soda ash with the soda ash in a predomi-- nating amount, which comprises preparing a soap and soda ash mlxture w1th an amount of water suflicient to dissolve substantially all of the soda ash ingredient, the proportion of water being substantially in excess of the amount desired in the finished product so as to render themixture free fiowmg to permit its beingbroken up into 1i uid drops by spraying and permitting its eing handled t rough pumps and pi lines with ordinary care without danger o solidification therein, spraying said soap powder mixture to thus subdivide it into drops, efl'ecting removal" of a portion of the moisture content of the sprayed soap powder mixture down to substantially 40% by bringing a current of heat-- ed moisture absorbing treating gas into contact with the sprayed particles of the said mixture in such manner that the said gas surrounds the sprayed drops absorbing moisture therefrom and entrains said drops and carries them along in concurrent flow while the said water absorbing action takes place, regulating the total moisture absorbing cacontent, effecting incorporation ofa major portion of said relatively high water content with the other constituents of the said soap powder mixture as water of crystallization to produce an ultimate product in apparently parently dry powder product from the treata ing gas to constitute the finished product.

- In testimony whereof I aflix my signature.

ROBERT L.. HOLLIDAY.

pacity of the treating gas relative to the total amount of water desir d to be removed from the product being treated to 'thereby' inhibit the removal of moisture from said particles of sprayed soap powder mixture while the said mixture still has a relatively high water 

